In drilling for oil and gas a rotary rock bit is threaded on the lower end of a rotary drill string. The drill string is lowered into the borehole and rotated, causing the bit to rotate and disintegrate the formations at the bottom of the borehole. These boreholes extend many thousands of feet into the earth and very often they extend many miles into the earth. When the rock bit fails, the entire drill string must be pulled from the borehole to replace the bit. The operation of pulling the drill string involves uncoupling the drill pipe sections that make up the drill string and stacking them in the rig. A new bit is substituted for the bit that failed and the sections of drill pipe are recoupled and lowered into the borehole until the bit is again in position for drilling. Such "round trips" of the drill string require substantial time and effort of the drilling crew and no actual progress is made in extending the borehole into the earth. The round trip time required to change a bit varies on an average of from 0.6 hour to 1 hour for every 1000 feet of borehole drilled. For a 10,000 foot well, 6-10 hours are required to change a bit. In deeper drilling the round trip time is, of course, greater. With operating expenses of the rig ranging from $70.00 to $400.00 per hour, the expense of changing a bit is substantial. The expenses of offshore drilling rigs are much greater. In addition, round trips present hazards to the crew and to the borehole and cause severe wear on the expensive drilling equipment. A reduction of the frequency and number of round trips while drilling is of critical economic importance in drilling. By increasing the quality, strength and performance of the drill bit, the number of round trips can be reduced.
In the prior art induction rock bit bearing hardfacing process, rework and scrappage is caused by variations in the temperature of the arm ball bearing raceway flange. The prior art process controls the temperature of a carbon crucible based upon the temperature of the crucible above the induction coil throughout the process and leaves the final temperature of the ball bearing raceway flange dependent upon magnetic flux density and time. The present invention controls the total energy applied to the ball bearing raceway flange and the final or maximum temperature it can reach.